November 2015

Barefoot running: Debate moves to developing feet

The most public battles about barefoot running and minimalist footwear have been fought over their use by adult athletes and the clinicians who treat them. There is, however, a separate discussion underway regarding barefoot and minimally shod running in children.

By Cary Groner

Much has been written about adults and barefoot running, including in LER,1,2 but little research has focused on child and adolescent populations, so opinions are at least as plentiful as facts. Nevertheless, many of those opinions come from credible sources who take a commonsense approach based on clinical observation and experience. Moreover, in the past few years, researchers have finally begun to clarify the biomechanical effects of footwear and running in kids.

Kids’ feet

When LER spoke to former Olympian Zola Budd Pieterse for an earlier article, she said one reason she could train and compete barefoot so easily was that she’d grown up that way in South Africa (see “The truth about barefoot running: It’s complicated,” page 20, November 2010).2

“For me, running barefoot was a lifestyle, not an option,” she said. “All the kids in South Africa run barefoot, even today. It’s just something natural.”

According to Mark Cucuzzella, MD, a professor of family medicine at West Virginia University in Morgantown who blogs about the issue, the decision is crucial to children’s development and future capabilities.

Research from Nike shows the dynamic arch continues to develop until children are about 7 years old, and that midfoot con­tact area dur­ing barefoot running also decreases over time.

“The bones in kids’ feet are malleable, so if shoes put tension on those bones that’s not aligned with where they want to go, the bones will assume that direction,” he said. “The question isn’t how to transition kids to minimalist shoes; it’s why should they ever be in footwear that bends the foot out of its normal position to begin with?”

What’s considered normal for children should simply be the natural state of the foot, Cucuzzella said.

“I don’t want to come across like some Paleo wacko; I don’t think everyone should be eating raw steak and walking barefoot to school,” he said. “But a shoe is a medical device for a foot. It affects your bones, your gait; it’s not like wearing a hat. So I think we should allow the foot to develop as naturally as possible for strength, mobility, proprioception, elasticity, response to the ground, coordination, control of the kinetic chain—all of those things.”

Cucuzzella’s theory comes into practice in his own house. His 10-year-old daughter refuses to wear any shoe that isn’t flexible enough to fold up and put in her pocket, he said. The track team at his son’s middle school now wears racing flats—not because anyone forces them to, but because they’ve tried various styles and decided they like them best.

One problem is that, as children enter adolescence, they become much more self-conscious about their appearance, and this can lead to suboptimal footwear choices, according to Cucuzzella.

“I just cringe when I see a teenager in middle school in high heels with pointy toes,” he said. “I see those kids later, in high school, and they have severe hallux valgus—they can’t rehab it with some stretching or taping, they’ve actually deformed their feet.”

The literature

Other clinicians have been making a similar case for years. In a 1991 paper in Pediatrics, for example, Seattle orthopedist Lynn Staheli, MD, surveyed anthropological literature and concluded that native people worldwide had far fewer foot problems if they lived their lives barefoot than if they wore shoes.3 Staheli added that “stiff and compressive foo­twear may cause deformity, weakness, and loss of mobility,” and that “shoe selection for children should be based on the barefoot model.”

Roughly a decade later, William Rossi, DPM, wrote that nearly all juvenile footwear was bad for kids’ feet.4 He contended that any shoe that confined the feet or included any sort of heel rise should be eschewed. For example, the thick soles common in baby shoes “prevent 80 to 90 percent of the child’s normal flex angle…thus denying the foot its normal step sequence.”

In recent years researchers have begun to describe the effects of footwear on children’s walking and running biomechanics in more detail.

For example, in 2008, German researchers reported that footwear limited midfoot motion during walking, and concluded that “slimmer and more flexible children’s shoes do not change foot motion as much as conventional shoes.”5

Then, in 2011, Australian researchers published a meta-analysis in the Journal of Foot & Ankle Research that examined 11 studies of more than 1200 children aged from 1.6 to 15 years.6 They reported that, in kinematic running studies, shoes were associated with significant changes, including a smaller ankle plantar flexion angle at heel strike; smaller plantar foot angle at foot strike; lower angular velocity of the knee; and lower swing-back velocity of the tibia. Significant kinetic changes included less tibial acceleration and shock wave transmission.

The authors also reported that, while vertical ground reaction forces were not affected by footwear, there was a trend for shoes to be associated with a reduced loading rate. Children wearing shoes were more likely to heel strike (97%) than those who ran barefoot (62%).

In later papers, the Australian team reported that shoes did not significantly affect running agility, but that, during propulsion, shoes had a “splinting” effect on the feet.7,8 That is, shoes reduced first metatarsophalangeal (MTP) joint motion during running from 31.5° to 12.6°, and midfoot sagittal plane motion from 27.4° to 9.6°. These limitations in midfoot motion may have lowered efficiency by reducing the windlass mechanism and the release of stored elastic energy, the researchers said. Although children partially compensated with increased ankle plantar flexion, this strategy may have increased the work of the triceps surae complex.

The lead author of the Australian papers was Caleb Wegener, PhD, who conducted the studies while completing his doctorate at the University of Sydney; he now does research and development for Sydney-based Mack Boots while retaining an honorary research associate position at the university.

“For most kids, walking and running barefoot means the arch rises over twenty degrees during the propulsive phase, but when they wear shoes, it only rises by about eight degrees, so it’s quite a large reduction,” he said. “When the arch rises, the foot shortens, but most footwear doesn’t shorten with it. And, when you put on a shoe and tighten it down, that has a binding effect; it pushes down on top of the foot as the foot is trying to rise. The effect on motion is a combination of these factors.”

Our conversation was interrupted by a shriek; it was Wegener’s young daughter trying to get at his laptop. She was, perhaps not surprisingly, running around the house barefoot. Wegener laughed and emphasized that, like Cucuzzella, that he’s not an anti-shoe zealot.

“Shoes have beneficial effects; the attenuating effect on load is probably beneficial, you protect the feet from cold and from sharp objects, and kids walk faster in them,” he said. “Those are good things, and we’ve been wearing shoes for thousands of years for those reasons. It’s all about having the right functionality in the footwear so the foot can still function as designed.”

Recent research from the Hospital for Special Surgery in New York City has produced compatible findings. In a 2013 study of early walkers published in the Journal of the American Podiatric Medical Association, for example, the authors reported that increased shoe flexibility promoted greater plantar loading, and that plantar pressures in the most flexible shoes were similar to barefoot levels. In conclusion, they speculated that this mechanical feedback might enhance proprioception.9

Developing biomechanics

Irene Davis, PT, PhD, is well known for believing less is more in such matters. Davis, director of the Spaulding National Running Center in the Department of Physical Medicine and Rehabilitation at Harvard Medical School in Boston, told LER: Pediatrics that, in general, the less interference with normal motion, the lower the likelihood of injury.

“There was an Indian study10 of kids from three different kinds of communities,” she said. “Flatfoot was least prevalent in children from an area where they went barefoot. If you don’t support the foot, the muscles get stronger; if you do, muscle demands decrease and the foot weakens. We need to be rethinking footwear in kids, because it changes the mechanics of the whole lower extremity.”

In a 2011 paper in the American Medical Athletic Association Journal,11 Davis wrote, “When children first learn to run, they naturally land on their forefoot with a relatively flat foot pattern. By the time they are four years old, and likely habitually shod, they have adopted a rearfoot strike pattern when they run.”

Davis acknowledged that developmental biomechanics isn’t her specialty, and said it would be interesting to know more about how young feet grow and change.

“I just think it’s important to allow the foot to function the way it’s supposed to throughout its development,” she said.

Investigators at Nike in Beaverton, OR, have analyzed foot loading in developing children aged 3 to 11 years as they ran barefoot, though they drew no conclusions about footwear as a causative factor. In a paper presented at the 2009 meeting of the American Society of Biomechanics in State College, PA, Nike researcher Martine Mientjes, PhD, wrote that the dynamic arch continues to develop until children are aged about 7 years, and that midfoot contact area during running also decreases over time.12 Moreover, increased loading as children age may affect midfoot contact area—increasing lateral contact—until they are aged at least 11 years. This may be due to increasing speed or muscle strength, coordination changes, or gender differences (boys had a broader midfoot than girls even allowing for weight differences).

In a second paper presented at the same conference, Mientjes reported that, at younger ages (3-5 years), about 80% of children landed on their heels when running barefoot; by the time they were aged 7 years, 93% were heel strikers, and, by 11 years, 100% were.13 This upended the researchers’ hypothesis that most younger children would land on their forefoot or midfoot when running barefoot.

Footwear and training

As with grownups, barefoot running isn’t a panacea for children, experts say.

“There are always tradeoffs,” said Peter Larson, PhD, a runner and blogger who performs gait analysis, offers footwear consulting, and coaches runners at Performance Health in Concord, NH. “When you reduce biomechanical work in one place, you increase it somewhere else. With barefoot running in adults, we’ve learned that taking off the shoes doesn’t necessarily make injuries go away; it just moves the susceptibility to different parts of the body.”

Although children are increasingly interested in distance running,14 Larson said that not many participate in it where he lives, partly because of long, cold winters.

“It’s mainly soccer—a lot of cutting and sprinting,” he said. “So when the season starts, coaches try to ramp them up to competition level, and that exposes them to a lot of loading quickly. Whatever shoe they wear, if it’s stressing them in a way they’re not used to, that may be an issue that isn’t faced by an adult who runs year-round.”

Larson’s own children—aged 11, 10, and 5 years—wear as little in the way of shoes as they can get away with.

“I wouldn’t put them in a mini version of a traditional running shoe,” Larson said. “I’m not opposed to cushioning, but I want them to be in something reasonably flexible that’s not going to constrict their feet.”

Seth Jenny, PhD, was so concerned about the lack of standards in children’s distance running training protocols that he developed a number of recommendations to help keep kids both interested and uninjured.14

“Youth running programs have exploded in the US, but it’s a little scary because we don’t know what’s safe,” he said.

Jenny, formerly an exercise physiologist with the US Air Force and now an assistant professor in the Department of Physical Education, Sport, and Human Performance at Winthrop University in Rock Hill, SC, believes children have lower injury risks than adults in some ways, and higher risks in others.

“I think that, because they weigh less, there’s less stress on the tissues,” he said. “But risks for overuse and repetitive motion injuries may be similar. If they have poor running mechanics or inappropriate footwear, it can certainly cause problems requiring intervention.”

As for shoes, Jenny isn’t convinced that minimalist is the way to go. He saw lots of airmen get injured trying to transition to them too quickly, and he has his own kids wear typical running shoes. His says that his 3- and 5-year-olds are already running 400-m races and getting a kick out of it—in both senses of the word.

Down the road

As children’s running biomechanics receive further study, presumably footwear recommendations will become clearer, as well. In the meantime, common sense suggests that what kids naturally gravitate to—bare feet when there’s little risk of injury or frostbite—may be what’s best for them.

Davis I. What can we learn from watching children run? AMAA 2011;(Fall):7-8.

Mientjes M, Pisciotta J, Lafortune M. Dynamic arch development: midfoot contact area and loading during running in children age 3 to 11 years. Presented at the annual meeting of American Society of Biomechanics, State College, PA, August 2009.

Mientjes M, Pisciotta J, Lafortune M. Foot strike contact location and foot loading during the development of running in children age 3 to 11 years. Presented at the annual meeting of American Society of Biomechanics, State College, PA, August 2009.